A multifunctional sodium alginate crosslinked polyethyleneimine (SAPEI) water-based binder with cross-linked network structure for lithium sulfide battery cathode was created using sodium alginate (SA) and polyethyleneimine (PEI) as the raw materials. The ability of the SAPEI binder for adhesion and polysulfide adsorption, as well as its effects on the composition and electrochemical functionality of the lithium sulfur battery cathode, were investigated. The findings demonstrate that the SAPEI binder has a stronger binding capacity than conventional commercial (PVDF) binder, and that the reaction's amide bond has an adsorption impact on polysulfide ions. After cycling, the lithium-sulfur battery with SAPEI binder had a more consistent microstructure and improved electrochemical performance. The specific discharge capacity is still 620 mA·h/g after 200 cycles of charging and discharging at a rate of 0.2 C, and the capacity retention rate can reach 72.5%, which is higher than that of a lithium-sulfur battery employing PVDF binder.